Autodyne circuit



April 9 1935 w. VAN B. ROBERTS 1,997,393

AUTODYNE CIRCUIT Filed Janfl, 195o Ey, i

WALTER VAN B. ROBERTS ATTORN EY `Patented pr. 9, 1935` flssmssa'? c tion of Delawarev p A Y" 14' claims; Mir presen'tfinvention relatesto heterodifne systems, andi-more particularly. to -a superheterodyne receiver'v employing-an autodvlne circuit.

j rtirhas. `been suggesteim" the past thatsuferiv hetercdyne: receiving circuits beconstructedso as to utilizearstautodynetub'e circuit.` That'isto say, the antennawas tcfbe coi-ipledto` a tube havingitwo iridependentftuned oscillation .circuits in itsinputg one of these circuits was to fbe tuned' y. tothe signal to bereceived, whilethe other Was-to iceV tuned to` the-ffrequericyfycf" the heterodyne oscillations to be einployedffor producing thefintermediate frequency.' Furthermore, thefjtwo cir; cuits were to be arranged so that Ytheyfdidfxiot in the heterodyne circuit.'Werelnotitoset up'oscil'- lationsin the signal circuit 'with' consequenlfradia`` tionirom the antenna. K

foi" uni-controlftuning`,' in a' ga'ng ofif condensers,

that in tnegbriuge .arrangements 'heretoforev used, such as Fig'. l herein,` no tv volsets Ofjcondenser gangcondenser" with' Vrotors y Y l atacommon-potential cannot be used.-

` devisedrneans' for, employing an autdyne circuitin a superh'eterodyrie receiver"wherein` no local energy is 4radiated yfrom! theaitenna, Iand wherein the rotors ofthe'signalrand localcircuts `'may be rrourited on the co'rrmo'nshaft of a bathtub housing Without having thecondenser rtors y at'diffe'rent potentials.` l A, y Another important objectofthe invention `is to provideA a" heterodyne circuit employingthel 40 autodyne principle, and means zfor` preventing radiation from the anten'r-1a`'by4 the tunedlocaloscillation' circuit, tliem'eansincluding. a tuned signa-lcircuitfcoupled to an indu'ctance, the latter being connected at one vend' thereof -tc the tuned local oscillation circuit so that'signal current 'does not producecurrent in Ythey local oscillation circuit;` Another obfject'or Itheirn'zentiori is to provide a frequencych'angi'ng circuit'inwhich the grid bias cf'theelectron discharge tube is securedfloy7 selfranged "inf the tube input th'V fed'into 'the signalcircuit.

prove generally the simplicity" andfefcifncyfoi affect each otherduringL tun-ingenti oscillations l However-Q trouble -isvencountredywlien ,tatitemptedto rnount the. rotors of' the signal `and local oscillation` condensers, Ion'fa cornrnon-` shaftV Accordingly," 1 have mventdlallr'ethd offand t "biasin'g'mears, rather than' by positive` ybiasing;- means,` and the signal and local circuits. souarl t no local energy is 'l (oratie-720:) l n frequencyV cliangingtcircuits. of the autotlyve"timef,` as employed particularly. superheterodyn -re ceiyersv', and toprovideavfreguency'changinglc cuit whichis not only-durable aiidjreliablefin.

operation, but is readily. adapted l eor'iorica'l ,5L

Fig'. 2.

connectionwith thert electrn discharge device l bjr, asuerneterodyne'receiver, and ,'wriicncirtuit" of simplicity.

ing thesignal circuit S to the desired signal fre- The circuit shown in `Fig. 1 is operated by tunquency, and tuning the local oscillation circuit O to a frequency which will heterodyne with the is connected in serieswith condensenor tube :signal frequencyr to produce a difference fre- `quency equal to the frequency to which the intermediate frequency amplifier is tuned. Of course, it'simplies the operation of the superheterodyne receiver when the vvariable condensers land 3V can be arranged in gang construction ina bathtub housing for shielding purposes, and the rotors of thetwo condensers mounted on a common actuating shaftv for uni-control. y l

` For example, one of theadvantagesto bese-j'- curedby ysuch construction is not only the simultaneous tuning of the two circuits, but the fact that the rotors of each of the condensers may beso relatively shaped that `a constant frequency 1 difference maybe maintained between the two circuits which yis equal `to the Aintermediate frequency being employed. However, actual eX-` perience'has shown thatythe circuit in Figui does not lend itself to such construction. That is v to say, the condenser rotors, inthe circuit of Fig.

1, cannot all be connected together on a common shaft in abath-tub shielding housing. l

, By designingr and arranging the circuit as shown in Fig. 2, :this disadvantagemay be effectively eliminated. "fThu's, in Fig. 2 there is shown an antenna circuit A'including a capacity I therein, and an anti-resonantsignal circuit S in series with the antenna condenser l. The signal circuit includes lthe, variable condenser,` I D and a coil L connectedacross the Variable condenser Condenser K, shunted by a high resistance R,

input capacity C', the latter being shunted by the tube input resistance. A blocking condenser B, and vthe' grid leakR, are employed' inv thegrid circuit to maintain the bias on the grid of the tube l, rather than employing the source which mightequally well have been employedforex-V ample in vplace of condenser B. l

'The local oscillation circuit O which includes the` inductance 2 and the variable condenser 3,v iis connected in series with a coil N, the latter being coupled at M to the coil L. The biasing condenser B is connected Yin series between the control electrode of tube l and the coil N. The

anode of the tube is energized from ksource B Y through the primary 6 of the Ytransformer M' the primary being shunted by the condenser 8, the

tickler, or feed back, coil I being connected in series with the primary (i and the source B, `and being further coupled to the inductance 2v of the" local oscillation circuit. As ini the case of Fig. l, the difference frequency ofthe combined signal and local frequencies is impressed uponthe secondary 9 lof the transformer M', and rthen amplii'led bythe intermediate frequency amplifier,

and the `aforedescribed subsequent utilization circuits and means. f d, i, Y

"Ilhe operation and advantages of the` invention willnow be described. vIf coil N were open cir- Hcuited, the grid of tube I would assume a potential which would be a definite fraction of the potential difference across coil L. Now, assume that coil N is connected in circuit, and coupled to coilv L ,sufficiently so that coil N has a potential difference generatedl between its terminals vdue to` current in coil L, which potential difference is exactly equal to the aforementioned grid potential. It follows that the potential at the bottom of coil N is zero as a result of current in coil L; hence, current in coil L does not produce any current in the oscillation circuit O.

Y And, therefore, from well known reciprocity theorems it follows that oscillations in oscillaquencies, can Vbe dispensed with entirely if it is preferred tobias thel grid by `other means.

While I havey indicated and describedv one arrangement for carrying my. invention into effect, it will be apparent'to one skilled in the art that my invention is by no means limited to the particular organization shown and described. but that many modifications may be employed without departing from the scope of my invention as set forth in the appended claims. For example, oscillations generated by separate means may be impressed upon the circuit O rather than be generated by circuit O itself in cooperation with tickler coil' What I claim is:

f1. In a receiver of the superheterodyne type wherein transmitted signal modulated carrier frequency energy is intercepted and combined with locally generated oscillationsto produce an intermediate frequency, an electron Adischarge device having an output circuit and an input circuitsaid input circuit being electrically connected toan antenna system, an oscillation circuit connected in said input circuit adapted to be tuned to the frequency of the desired incoming carrier energy, asecondoscillation circuit, means for connecting said circuit in said input circuit,

means for coupling the output circuit of said Cil space discharge device to said second named os- K cillation circuitto facilitate the transfer of energy from said output circuit to said input'circuit 'for producing oscillations, said second named oscillation; circuit having means for controlling the frequency of thelocally generated oscillations, said connecting means for the second oscillation circuit Acornlrrising a link circuit coupled to the rst named oscillation circuit, said coupling being arranged so as to provide a voltage at one terminal of the second named tuned circuit tomaint'ain vthe terminals of said secondV named ytuned circuit as respects its connection in the input circuit of said space discharge device at zero potential with respect to each other and one terminal of the `rst named tuned circuit.

2; In combination an electron discharge device having an input circuit and an output circuit.

said input circuit thereof being linked with said output circuit to facilitate the transfer of energy from said output circuit to said input circuit q thereof for producing oscillations, a tuned cir- '4 cuit for controlling the frequency of said oscillations connected in said input circuit, a second tuned circuit tuned to a different frequency than said first named tuned circuit also connected in said input circuit and means for eliminating couping between said two oscillating circuits through transferred thereto-,from'saidsecond namedtun d;

theinherentl capacity thi-gspacedischarge--de#- vi'ce comprising 'a link circuiti coupled' to the sec ondinamedituned circuit and/*connected 'in` series-- with the first namedjitunedf 'circ-uit across thefirr- 1 putof'the Vspace discharge device-for-oppos other' through` the -said inherent capacity `of the] space discharge- 4device` whereby 'said two` tunedci'rcuits maybe operated atr very nearlyfthe'-same'"` from oneitothe other; u I

3: In an; auto-dyne type hcircuit, adapted!v for use asv af source of f `locally generated* oscil-latijons'l as a frequency changer Vs.uperhfeterudyne type circuits:v an' electron;` discharge jdevijcei'havingani inputV circuit `and an output" circuit, ,said-input cirouitthereof being linked Withsa'i'd'outputoirfrequencyA without'the' transference 'of ijrenergy?" cuit to facilitate -theV transferer-energy from; s aid output circuit t0- saicf input,- circuit-"merecr' fer-g producing os'cillations;` a' tunedL circuit' in said inj y put" circuit for` controlling: thei'frequencyfof js d1'A oscillations, a second"tun'edi"circuit` tune 'af dii'fer'ent frequency from'said iirstinamed"circuit:Y also connected tosaid-inputoircuit;` 'capacity-'bee tween said two` tuned circuits including theL natural capacity inherentbetweenthe 'various elements of the space discharge'de-vigcej saidci'rcuits bein'g traversed` byfcurrentsof, such/high" l frequency as, to make appieci'ableH tlre coupling between saidtun'edcircuitsgdue to thesaidca` pacity" vand' throughwhich coupling. high* fre-` quency energy mayv be transferred*fromone'off saidftuned circuits tothe other and means `com-111 prising. Ia linked circuit vadapted to Vhave energy i circuit connected in said input circuit for op ing" energyV transferredq,` from said second nam, d' circuit through thefspace discharge "device-ca'- pacites to Said first named Qtuned "circuit where#` by said two ltunedcircuits may` be operated *at* veryy nearly tht-iv same frejquencyg;` ufitli'out'ithe;` transference of' energy from one toythgeotherl 4; In ,a receiverV ofthe superheterodyne type wherein transmitted i signal` modulated-:j carrier, frequency energy isinterceptedat the receiver and combined with locally generated oscillations to produce an intermediate? frequency' and wherein itis' desirable to havegtleffrequency ofthe locally generated oscillations closely, approxi,-

, mate ythe frequencybfjthe carrier fener'gm, ank

electron discharge deviceA having an input circuitl adaptedto be "electricallyr connected t'ojan` anv tenna system, an output circuitf, saidiput cir.- cuit being linked with saidoutputlcircuitto facili itate the transfer. of energy, from.; said output circuit to saidinpu't circuitiforproducing oscilf' lations,` atuned circuitfinfsaidfinput circuit for controlling vthe frequency rof said last-named oscillations, a. second tunedcircuit in fsaidiinput circuit tuned" to the frequencyof the carrier'enf` ergy, electrical coupling between said.' tWotuned circuits including the naturaljcapacity inherent between various elements of A the space discharge;v

device and throughwhiclrcoupling"energy maybe transferred from saidffirst Anamedv tunedcircuit to said antenna system'andimeansrcomprising a linked circuit "adapted to `have energytransferred thereto from `said secondnamed 'tuned-circuit for opposing energy transfer-redl from said first fnamedftuned circuitt'hrough--sa-idfelectrical'cou- *l pling to said antenna systemwhereby` the-locally generated oscillations are-substantially preventedfrom --b'eing-conununicated toi-the sai/df-antennal o system.

5i f a recei-inerf-` cf-v thet isuperl-ieterodyne type frequency# yen'f'erg'y Vis interceptedv and"Y combine@ with-locally generatedv oscillationsi tcproduce-an; intermediate frequency, an electron dischargeguce c uit said input circuit-1 being coupledY to ani antennasystem; an oscillation circuitl'including a: variable condenserhavingf a stator and'w a rotor wherein transmitted signal; modulated-Jcarrierli connectedinsaidinputcircuiti adapted-' to'- beV tuned to fthe*- frequency of the desi-red incomingcarrier energ-y,^a secondi oscillation circuit in@v cludi-ng a condenser` having arotorfandastatorgi means-for connecting- 'saidC circuit in said f inputf circuit, means for" coupling the `outputcircuit-'ofiv said space f discharge y device to i the input lcircuit!` thereof" to-facilitate-the transfer of energy froml i said output* circuit-to said iinput circuit` for pro-- dwing-oscillations; said condenser in-saidisecondE named-1 oscillation.: circuit comprising 1r1ear1s1-Iory controlling the-frequency off the locally generatedf oso-illations4 fsaidf: connecting* means for thefsecondv oscillation circuitcomprising aflink?` circuiti coupled-to the-first namedoscillation circuit and arranged iso as to transf-erv electrical(energy-from asf-to maintain? the terminals-l of said seccnd"` named tuned circuit asrespects itswconnectionf inY ther-input: `circuit of said space discharge device-r at the same "potential as oneterminal ofthe-'firstl nanre'd tuned circuitwhereby.V the -rotorslA of i said two condensers faremaintained at the same poeVV tential and a uni-control` means for varying-said twoicondensers simultaneously?.`

`-`-6-`. In ai signalling system, an 'electronicf tup/e;v input and output circuits therefor, a pair-offdif'e-` ferentlytuned oscillation Acircuits in sai-d input' circui-tjbcth thereof being adapted toA impress voltage-'developedtherein upon the input-"elee- Yr-nents of-jf the tube', means for `connecting aA tere to" oppose the energy 1 vtransferred through l said` inherent coupling.

put and output circuits therefor, Ta pai-r ofdi-'ferentlytunedoscillation-circuits in saidinputci-r'- l cuitboth'fthereof-beingadaptedv to impress vol-f` l tages developed ltherei-r'i-uponj thel input elements of the tube, tuning means for saidosclllationfc-ircuits comprising fiked and movable elements,

means forconne'ctingaf'terminal `of-eachv off-said oscillation circuits to,a`poin-t"-of fixed potential whereby the movable-'elements' of said tuning means may be: `connected together by a vcom-'mon operating means, coupling between said circuits including the natural capacity-'inherent between different portions ofv said-` system, said-*circuits being traversed bycurrentsof suchhighfre'- quency as to make appreciable `the inherentcouf pling between them `and through `which "coupling energyfrom ,one -ofsaidl` oscillation circuits may be transferred to ythe` other thereof-,f means Y-for connecting the otherternnnals--of-f said*A oscilla@` tion*circuits;said'lastlnamedfmeansf-includirlg-)a device, for impressing energyfrom one oscillation circuit to the other of phase and amplitude tooppose the energy transferred through said inherv ent coupling.

V8. Ina signalling system, an electronic tube,v

input and output circuitstherefor, a pair of diffferently tuned oscillation circuits in said input circuit both thereof being adapted to impress Voltagefdeveloped therein-upon `the inputfele-` ments of the tube, tuning condensers for said oscillation circuits, each thereof comprising stator and rotor elements, means for connecting the ro-V tor lside of each` of said oscillation circuits to a' point, of lfixed potential thereby permitting the i rotors of said tuning condensers to be electrically connected: by a common operating means,vcou pling between said circuits including the natural capacity .inherent between the various l elements of said system, said circuits being traversed by currents of suchhighfrequencyas to make appreciable the inherent coupling between them and through which coupling energy from one of said oscillation circuits may be transferred to the other thereof, means for connecting the other" circuit ,of rsaid tubey to one `of said oscillation.

circuits to facilitate the `transfer of energy from said output circuit to saidoscillation,circuit for producing oscillations of a` frequency determined by. thetuning of said oscillation circuit, means for connecting a terminal of eachof said oscillation circuits to apoint of fixed potential where-V by the movable elements of said tuning means may be connected together by common operating means,- coupling between said ycircuits including the natural capacity inherent between different elements of said system, saidV circuits being. traversed by ycurrents of such high frequency as to make appreciable the inherent cou-V` pling between them and through whichv coupling 4energy from one of the oscillation circuits may be transferred to the otherl thereof, means for connecting thev other terminals of said oscillation circuitssaid last named means including a device for impressing energy from one oscillation circuit to the4 other of phase and amplitude to oppose the energy transferred 'through' said ininput elements of the tube, tuning means for herentccupling. Y o y Y l, 10, In asignalling system anelectronic tube,

input vand output circuits therefor, av pair of differentlytuned oscillation circuits in said input circuit both thereof being,k adapted to impress voltage components developed therein upon the each of said oscillation circuits comprising xed and ymovable elements, va source of signalling energy, means for connecting oneIoI `said oscilof said oscillation circuit, means for connecting a terminal of eachV of said oscillation circuits to a point of` fixed potential whereby the movable elements of said tuning means may be 'connected together,` by common operating means, coupling between said circuits including thev natural capacityinherent between different elements of said system, said circuits being traversed by ,currents of such high frequency as to make appreciable the inherent coupling between them and through which coupling `a portion of said produced energy maybe Vtransferred back to said source "of signalling energy and radiated therefrom, means for connecting the other terminals of said oscillation'circuits, said last named means including a device forvtransferring energy from one` oscillation circuit to the other'of phase andl amplitude .to oppose the energy transferred through said inherent coupling.V o' o l 1l. Ina signalling system an electronic tube, input and output circuits therefor,a pair of differently tuned oscillation circuits in said input circuit, both thereofv being adapted to `impress voltage components developed therein upon the.

input elements of the tube, tuning condensers for said oscillation circuits each thereof coin,-v

prising stator and rotor elements, means for connecting the rotor side terminals of each of said oscillation circuits to a point of fixed potential thereby permitting the rotors of said tuning between the various elements of saidfsystem, said circuits being traversed by currents'of such high frequency as to'make appreciable the inherent coupling between them and through which co'u-` e pling energy from one of said oscillation circuits may be transferred to the other thereof, means for linking the output circuit of said tube to one of said oscillation circuits to facilitate the transfer of energy from saidoutput circuit to said 0scillation circuit for producing `oscillations of a` frequency determined by the tuning of Vsaid oscillation circuit, a source of` mcoming signalling energy, means for coupling the other`of said oscillation circuits to said source, means Vfor connecting the `other terminals of` said oscillation circuits, said last named means including ka de- Vice for transferring energy from one oscillation circuit to the' other of phase and amplitude to oppose the venergy transferred through said in'- herent coupling and an intermediate frequency circuit associated 'with said output circuit,

12. A heterodynereceiver comprising an antenna, a frequency changing tube, a resonant signal circuit between the antenna and tube inputv including a Variable condenser, a local oscillation resonant circuit coupled to thetube vand including a variable condenser, said two resonant circuits having inherent coupling between them through which' inherent coupling, energy in one circuit is transferred to the other circuit, energy transfer means including a coupling coil between the local and signal circuits for transferring energy from one `circuit to the other in a sense to oppose the effect of `the, renergy transferred through the inherenticoupling between the two resonant circuits whereby said two circuits may be made resonant to frequencies'diifering from each other only by Asmall amounts, and means for maintainingoone` terminal of onel of said condensersat the same fixed potential as a terminal of the other condenser. Y o

. v13. In a heterodyne receiver a frequency chang- Leemans` ing tube having input and output circuits, said input circuitincluding a resonant'signal circuit having a variable tuning means adapted to tune said resonant circuit toany one of a plurality of signal frequencies within a predetermined band,`

`cuits for `transferring energyfrom one of said circuits to the other thereof in a sense to oppose the eiect of energy transfer through theinherent coupling between the 'two circuits whereby said two circuits may -be made resonant to frequencies differing from each i other ,only by Very small amounts and means for maintaining one terminal of one of said condensers at the same fixed poten-'- tial as a terminalof the other condenser. i

14. Ina receiver ofthe superheterodyne type, a frequency changer circuit including an electronic tube provided with input and output circuits, a resonant signal circuit in ysaid input circuit said resonant', signal circuit including a variable condenser, a second resonant circuit inthe input circuit of vsaid tube said second circuit including a variable condenser fortuning the circuit to the heterodyning frequency, said two r,resonant cir-` cuits having inherent coupling between them `through which coupling energy in one circuit is `transferred to the other circuit, ,coupling means .between said two resonant circuits for transferring energy from one circuit tol the other in` a j sense to oppose the` effect of the energy transferred through said inherent coupling to thereby permit said two resonant circuits to be made resonant to frequencies differing from each other only by small amounts said condensers being arranged so that `oneterminal of one and one terminal lof the` other ,are at `the same fixed potential to v thereby permit uni-control of the condensers.`

WALTER VAN B, ROBERTS. 

